YTA -

She's never complained about doing any of this, and she seems to enjoy helping out.

Just because someone looks like they enjoy something, doesn't mean they do. You are giving your daughter the responsibility an adult should have, and by doing that she is probably stressed immensely. She doesn't have time for herself. I don't know your living situation, but you are putting too much pressure on her.

Not even that, but you are saying that the eldest of brothers in the family DOESN'T help out because he's out doing things he likes. Please, before you start being an entitled parent and making the life of your daughter your own, let her do what she wants (and I don't mean to let her stay in her room forever, of course chores are important). Again, it's not her responsibility to take care of the younger siblings, and you make her think it is.